1. Field of the Disclosure
The present subject matter relates to vaginal and intrauterine brachytherapy tandem and ovoid implantation systems and methods employing same. More particularly, the present subject matter relates to such systems wherein the tandem has a detachable distal section that is disposable and intended for single-patient brachytherapy use, thereby allowing the single-patient distal section to maintain intracavitary placement for multiple treatment sessions and in between them, while the remainder of the system is removable in between these multiple treatment sessions.
2. Description of Related Art
Numerous devices and methods are known for intrauterine brachytherapy use. Many of these incorporate a tandem delivery tube and an ovoid colpostat. Often, dual ovoid colpostats are included and generally flank the tandem delivery tube. With this general approach, multiple delivery paths are available for treatment of different intrauterine locations.
Radiation oncology intracavitary brachytherapy practitioners and researchers have developed various systems. In the Manchester system, for example, a tandem and two ovoids are available in differing diameter sizes. In the Fletcher system, the ovoid colpostats have internal shielding, and polymer caps can be added to increase diameter. Different styles of tandems are available, having different curvatures and/or lengths, and a yoke attaches the tandem and ovoids together and facilitates maintaining proper positioning during treatment. Other systems include the Madison system, the Paris system and the Stockholm system. Typically in each of these systems, the tandem is inserted first, followed by the ovoids or other treatment components or devices. Typical treatment patterns or regimens follow multiple doses, and thus multiple intrauterine insertions and removals of the equipment are spaced apart in time by non-treatment intervals that vary depending upon the oncology protocol. Those application or treatment times typically vary between about five to twenty minutes. Usually the total treatment time is two or three days, with multiple treatments and non-treatment intervals proceeding during this timeframe.
Procedures for treating uterine or cervical carcinoma with tandem and ovoid systems and implant procedures typically follow a protocol calling for a series of three to seven implants, such as when following high dose rate (HDR) brachytherapy. At times, the oncologist may choose to use a low dose rate (LDR) brachytherapy regimen, typically based on cesium delivery as 137Cs. For HDR brachytherapy regimens 192Ir is frequently used because of its high specific activity. Other isotopes are available and used as warranted. The degree of treatment is measured in terms of units of radiation exposure (in roentgens or Gray or Gy) that are prescribed at specific points, termed A and B, within the pelvis. Details in this regard are known to radiation oncologists, medical physicists and other medical professionals experienced in brachytherapy. For example, in an early system (the Manchester system) point A can be at a location 0.2 cm lateral to the center of the uterine canal and 2 cm from the mucous membrane of the lateral fornix in the plane of the uterus. In that system, point B is defined as 0.5 cm from the patient's midline at the same level as point A. Point A can be considered a location of the paracervical triangle, while point B concerns the regional (Obturator) lymph nodes. An objective is to provide reasonably constant and predictable dose rates at each location, as applied by the isotopes of the tandem and ovoid system. An exemplary dose rate to be provided at point A is between about 50 and 55 cGy per hour. Specifics as to average doses at particular locations, such as point A and point B, generally are known to the medical professional.
Accordingly, it is clear that intracavitary brachytherapy such as that used in treating vaginal, uterine and cervical cancers needs to be exacting and specific in dose rates, durations and radiation target locations. Oncology treatment systems and methods such as tandem and ovoid combinations demand dosage rate and location precision during intrauterine brachytherapy. In addition, the closeness of tissues not intended to be irradiated should be taken into consideration. For example, it is important to minimize, if not eliminate, radiation exposure to the bladder and rectum. Generally, tandem and ovoid positions are noted on X-ray images in order to ensure intended placement and to allow the medical physicist or professional to generate a radiation treatment plan specific for this placement and for the particular anatomy and disease location and severity for the particular patient and for this treatment event.
It will be appreciated that tandem and ovoid colpostat delivery systems can be used in brachytherapy that is applied manually or remotely using remote afterloading systems. In remote afterloading systems, the radioactive materials are delivered from a safely contained source by way of hollow tubes to hollow portions of the tandem and ovoid components. Radioactive material can be in the form of wires or seeds. In such systems, the radioactive material is delivered via remote control, such as by operation of a motor, after the medical professionals all are removed from the treatment room. Such remote delivery equipment moves the radioactive dose into the applicator (such as an ovoid or other colpostat or tandem) already positioned within the body cavity.